A display screen is one of the most common input and output devices for electronic equipment. The display screen has a capability of displaying texts, images and videos.
Currently, the display screen usually has a wide visible angle approximately in a range of 120° to 170°. When a user uses electronic equipment in a densely populated place such as a bus and a subway, it is probable that other persons around the user may catch sight of the contents on the display screen, resulting in privacy leakage for the user.